We’ve covered Dr. Adam Gazzaley director of the Gazzaley Lab at UCSF previously so I was excited to see he was being interviewed for one of my favorite podcasts, ShrinkrapRadio by Dr. David Van Nuys. I’m a big fan of Dr. Dave and have been enjoying his interviews with top psychologists for years. (Especially those with Jungian analysts.) I’ve clipped an excerpt of the interview that deals directly with tDCS and brain stimulation below but I highly recommend checking out the entire episode as it provides an excellent framework for understanding the notion of brain training using technology including video games designed specifically to enhance memory and cognition.

In this clip Dr. Gazzaley lays out what clearly is the near-future of non-invasive brain stimulation… You’re playing a video game that has been optimized to enhance working memory (for example). At the same time your EEG is being monitored for brain activity. According to the EEG data, tDCS (tACS, tRNS etc) is activated for the purpose of enhancing activity in that region of your brain. As your game accuracy increases, the game adapts to increase difficulty to an optimum training level. Loop!

Cognitive and emotional functions
LLLT via commercial low-power sources (such as FDA-cleared laser diodes and LEDs) is a highly promising, affordable, non-pharmacological alternative for improving cognitive function. LLLT delivers safe doses of light energy that are sufficiently high to modulate neuronal functions, but low enough to not result in any damage. In 2002, the FDA approved LLLT for pain relief in cases of head and neck pain, arthritis and carpal tunnel syndrome. LLLT has been used non-invasively in humans after ischemic stroke to improve neurological outcome. It also led to improved recovery and reduced fatigue after exercise. One LLLT stimulation session to the forehead, as reported by Schiffer et al. (2009), produced a significant antidepressant effect in depressed patients. No adverse side effects were found either immediately or at 2 or 4 weeks after LLLT. Thus, these beneficial LLLT treatments have been found to be safe in humans. Even though LLLT has been regarded as safe and received FDA approval for pain treatment, the use of transcranial lasers for cognitive augmentation should be restricted to research until further controlled studies support this application for clinical use.

Especially in light of the recent Aldis Sipolins study which found no transfer (improvement to fluid intelligence) with his tDCS/exercise protocol, I think it’s smart to keep our eye on tACS. Although far less researched, I’ve noticed consistent reports of positive effects. Google the article title and you can find a few links to full pdfs.

The results showed that active theta tACS affected spectral power in theta and alpha frequency bands. In addition, active theta tACS improved performance on tests of fluid intelligence. This influence was more pronounced in the group of participants that received stimulation to the left parietal area than in the group of participants that received stimulation to the left frontal area. Left parietal tACS increased performance on the difficult test items of both tests (RAPM and PF&C) whereas left frontal tACS increased performance only on the easy test items of one test (RAPM). The observed behavioral tACS influences were also accompanied by changes in neuroelectric activity. The behavioral and neuroelectric data tentatively support the P-FIT neurobiological model of intelligence.

To clarify the takeaway message: we weren’t actually training fluid intelligence. Fluid intelligence has been shown to rely on fundamental cognitive abilities like working memory and attention, and the games were designed to train those underlying abilities. Training on fluid intelligence tasks would be like teaching to the test.

In a talk, “Can HD-tDCS Enhance Cognitive Training”, Aldis Sipolins describes a ‘wildly ambitious’ cognitive training study called the INSIGHT Project. Funded by IARPA, the study combined rigorous exercise and HD-tDCS-enhanced cognitive training in an attempt to increase ‘fluid intelligence’. 518 subjects, half of whom underwent pre and post fMRI scanning, undertook a 16 week course of combined exercise and brain training. The results? Anodal HD-tDCS improved performance on 3 of 6 brain-training video games but had no effect on transfer, i.e. the improvements did not transfer to general intelligence. As a result tDCS will not be a part of the study moving forward.

Partnered with Aptima to create a suite of six brain-training games. Games were ‘adaptive’, i.e they increased in difficulty as the subject’s performance improved.

Montage used was 2 x 2 (4 electrodes) designed by Soterix to affect DLPFC (dorsalateral prefrontal cortex). Dosage was 2mA for 30 minutes. Training started once current ramped up.

BOMAT (bochumer matrices) test was used to determine whether enhanced game performance transferred to fluid intelligence.

A future study on the INSIGHT Project will include a Mindfulness meditation segment and include nutritional supplements (brain shake).

In a recent Reddit thread when asked what he’d do differently, Aldis Sipolins said:

1) Include a cathodal group, with the hope that it impairs performance. Vince Clark suggested that impairing performance during cognitive training may have led to greater transfer. Kind of like how strapping weights to your body when you train makes it easier to move once you take them off.

2) Include a tDCS group that doesn’t complete the exercise intervention. It’s possible that exercise masked the effects of tDCS.

Excellent study. Confirming once again how early we are in our understanding of tDCS. (emphasis below are mine).

Although these studies all report positive findings there is still considerable variability in terms of the pattern of effects, paradigms used and tDCS parameters. For instance, stimulus intensity, duration, tDCS electrode montage are inconsistent. The most consistent pattern in the published literature has been to report significant improvements in WM tested in verbal n-back tasks and anodal tDCS to the left DLPFC. In other cognitive realms a patchwork of findings is emerging revealing consistent effects in memory, deception, and cognitive control. However, there are exceptions and forays into different tasks, populations, and parameters have produced different patterns of results.

Interesting especially in relation to Michael Weisend’s success using F10 in skill (target recognition) acquisition. That the research is going in this direction is encouraging. I expect we’ll have a much better understanding of various cognitive enhancement strategies over the next few years.

We compared effects of 30 min prefrontal and parietal stimulation to right and left hemispheres on subtask performance during the first 45 min of training. The strongest effects both overall and for ship flying control and velocity subtasks were seen with a right parietal C4, reference to left shoulder montage, shown by modeling to induce an electric field that includes nodes in both dorsal and ventral attention networks. This is consistent with the re-orienting hypothesis that the ventral attention network is activated along with the dorsal attention network if a new, task-relevant event occurs while visuospatial attention is focused Corbetta et al., 2008. No effects were seen with anodes over sites that stimulated only dorsal C3 or only ventral F10 attention networks. The speed subtask update memory for symbols benefited from an F9 anode over left prefrontal cortex. These results argue for development of tDCS as a training aid in real world settings where multi-tasking is critical.

Before you strap a tDCS device on your head in order to learn something new, have you studied Spaced Repetition or Interleaving? Have you mastered software like Anki? Or language learning techniques? As the paper quoted below makes so clear, tDCS adds another very complex set of variables to the notion of accelerated learning. While it may be practical for the military to be pursuing optimized tDCS-enhanced training methods for very specific skill sets, I do think we’re years away from practical DIY learning protocols involving tDCS.

Although tDCS shows promise as a training method, important questions remain unanswered. To maximize effects on training, optimal stimulation schedules i.e., every day, twice a week, etc. need to be determined. Juvina, Jastrzembski, and McKinley 2013 used a computational modeling approach to predict the optimal tDCS scheduling, but empirical validation is required. Second, at what point in training should tDCS be applied? One study showed that tDCS was more beneficial in the early phases of training Bullard et al., 2011, whereas another showed benefits at all stages McKinley et al., 2013. Importantly, these studies involved different learning tasks, so it is possible that the optimal time point for tDCS efficacy is task dependent. Likewise, different electrode placements may be optimal for different stages of learning. Third, how long is the learned information retained, and does this change with repeated doses of tDCS? Initial evidence suggests that tDCS-induced improvements in learning are retained for at least 24 hr Falcone et al., 2012; however, there is little evidence of exactly how long the new knowledge is retained. Finally, the “gold standard” of any training technique is not only whether it is effective in accelerating learning on a particular task but whether its effects transfer to others tasks within the same cognitive domain Dahlin, Neely, Larsson, Backman, & Nyberg, 2008; Strenziok et al., 2014. TDCS will ultimately need to be held to this high standard

An intelligent introduction to tDCS and TMS in the context of Cognitive Enhancement. Dr. Roy Hamilton (at around 19:00 in the video, the beginning is basic intro boilerplate) discusses studies which demonstrate significant positive cognitive effects in healthy individuals. I especially liked Dr. Hamilton’s take on the concerns and potential risks of non-invasive brain stimulation which he discusses towards the end of his talk.

Brain imaging suggested that the best way to do this would be to stimulate the motor cortex while the volunteer was doing the task. But McKinley and his team added a twist: after the stimulation, they use tDCS in reverse to inhibit the volunteers’ prefrontal cortex, which is involved in conscious thinking. The day after the stimulation, the volunteers are brought back for re-testing. “The results we’re getting are fantastic,” McKinley says. People getting a hit of both mid-test and inhibitory stimulation did 250% better in their retests, far outperforming those who had received neither. Used in this way, it seems that tDCS can turbo-boost the time it takes for someone to go from being a novice at a task to being an expert.

Neurolectrics (Starstim device) published a white paper (pdf) in October 2013 that nicely collects pretty much all we know to date about tDCS and cognitive enhancement. I was reminded of this while visiting their montages page on their new wiki. Quoted is from the Chi / Snyder 9 Dot study (pdf).

Brain stimulation enables the solution of an inherently difficult problem – Certain problems are inherently difficult for the normal human mind. Yet paradoxically they can be effortless for those with an unusual mind. We discovered that an atypical protocol for non-invasive brain stimulation enabled the solution of a problem that was previously unsolvable.The majority of studies over the last century find that no participants can solve the nine-dot problem – a fact we confirmed. But with 10 min of right lateralising tDCS, more than 40% of participants did so. Specifically, whereas no participant solved this extremely difficult problem before stimulation or with sham stimulation, 14 out of 33 participants did so with cathodal stimulation of the left anterior temporal lobe together with anodal stimulation of the right anterior temporal lobe. This finding suggests that our stimulation paradigm might be helpful for mitigating cognitive biases or dealing with a broader class of tasks that, although deceptively simple, are nonetheless extremely difficult due to our cognitive makeup